1. Radon: What We Have Learned From Retrofit Studies
Stacy Gloss, research specialist
Indoor Climate Research and Training
University of Illinois

2. In accordance with the Department of Labor and Industry’s statute 326
In accordance with the Department of Labor and Industry’s statute , Subd. 11, “This educational offering is recognized by the Minnesota Department of Labor and Industry as satisfying 1.5 hours of credit toward Building Officials and Residential Contractors continuing education requirements.” For additional continuing education approvals, please see your credit tracking card.

3. Learning Objectives Identify radon zones on EPAs radon zone map.
Describe differences on radon levels from two residential ventilation strategies.
Recognize some patterns of correlation between temperature and radon.
List pros and cons of different radon test methods.
Discuss patterns of variability of radon from multiple factors.
Describe impacts of different retrofit measures.

4. Topics What is radon? How is it identified? (test methods)
What’s does EPA tell us to do when practitioners find radon in a home?
What are findings from studying radon in residential retrofit settings?
Conclusions and Discussion
I know that I’m the only person standing between you and your lunch.

5. Disclaimer: I am not a Ph.D. scientist. I’m not a policy wonk.
I’m not an epidemiologist.
Involved in research
Fits easily in crawl spaces
I have been spending some time in people’s crawlspaces and basements testing radon before and after residential retrofits for research.
I look forward to sharing with you what I’ve learned.

6. (Raise your hand. Don’t be shy.)
Survey Question #1
Do you consider yourself to have moderate to advanced level of radon knowledge?
(Raise your hand. Don’t be shy.)

7. Survey Question #2
Have you ever tested a home for radon?

8. Survey Question #3
Are you familiar with active soil depressurization and other radon mitigation techniques?
This is not a presentation on home radon mitigation.

9. What is radon?

10. What is radon?
Naturally occurring radioactive gas that can cause lung cancer.
You can’t see or smell or taste radon.
Radon can have a big impact on indoor air quality. (EPA)

11. Radon Science Chemical element with symbol Rn. Occurs naturally as a
decay product of radium.
Half-life of 3.8 days.
Alpha particles from Ionizing Radiation are dangerous to human health.
It lies within the noble gas column on the periodic table, which means it is inert and nonreactive. Radium is, however, radioactive. Radon occurs as an intermediate decay product from uranium or thorium as they decay to lead. The half life of radon is about 3.8 days. This means that it takes about 3.8 days for half of the radon available to decay. In its decay process radon loses two protons and two electrons. Losing two protons results in polonium on the periodic table.
Beta particle doesn’t realy have mass but it allows the changes the atomic number up by 1. Alphas jump down by 2, beta’s cause jumping up by 1.

12. Uranium decay chain Thorium to radium to radon.
Beta particles – a neutron becomes a proton or vice versa so it jumps by atomic number of 1. They all end at lead.
Back in 70s they called them radon daughters / radon progeny. Radon is a gas, you can breath it. You’ll have it in your lungs. It pops an alpha decay and an alpha particle is like a helium nucleus. You can blow up a latex balloon and the helium stays in in it. Alpha particles are ejected with a certain acceleration. They give a physical blow to whatever is near by. Radon gives polonium. It’s a solid. It can land on a lung cell. An alveolis. A radio active element atom sitting on a lung cell. It’s radio active and can blast an alpha particle out. It creates condition for blasting alpha particle out of polonium atom going after cell its sitting on. It could hit the DNA of that cell. It can damage DNA. 10 x a min DNA is checked and repaired. A lot of this stuff can do a whole lot of damage. Presumption is risk that one of the radon daughters is sitting in lungs and it will blast with alpha particle.
Small risk that DNA is changing into something else. Ignoring that DNA repairs itself. But we also know that a lot of radiation can kill you.

13. What are we concerned about?
Radon decay products – alpha particles.
Alpha particles are solids and can stick to surfaces such as dust particles in the air that are breathed in.
Radon can get into the lung through respiration, and can decay to radioactive solids or radon progeny.
Can damage lung cells and cause lung cancer
Alpha particles have mass. The atomic weight of helium. 2 protons. It’s basically a helium nucleus. It’s not the presence of alpha particles it’s the punch of the alpha particle.
Can be smack on the cell wall they they decay and that is the presumed risk.
And we know at high levels it does. No doubt.

14. Radon measurement units
Most common unit in U.S.
pCi/l = picocuries per liter
For each pCi/l there are 2.2 radioactive disintegrations per minute (source: radon-faq.com)
EPA Threshold 4.0 pCi/L
For more information go to:
Pico-curie is another estimate for bequerel – a radio active decay event.
Radon does have mass and you can have mass per mass concentration but we’re not sampling radon. We are measuring alpha decays – radio active events. Alpha decays. If you find me saying ‘concentration’ its sort of the same way. Its’ measured by ‘pops’ not by ‘pounds’ – (Out goes the alpha particle)
Alpha decay. Big nucleus of radon atom is unstable in a way that alpha particles pop off it. When they pop it’s radio active disintegration.
Bequerel is a radio active disintegration per second?
One becquerel is defined as the activity of a quantity of radioactive material in which one nucleusdecays per second. A decay or disintegration is the same thing. 1

15. Where is radon?

16. EPA Radon Map
A fair bit is mountains but some areas in the plains where some soils tend to be high. Clearly some soils cause this not in the mountains. Granite is often related. Appalahcians, Rocky’s,

17. Add arrows for Minneapolis and Duluth

18. EPA Radon Policy Developed in early 1980s
Recommend mitigation for levels > 4 pCi/l
1960s and 70s was the big atomic era. Lots of uranium mining. The mining was often done on native American reservations. When you mine for uranium, you go into uranium rich soils and try to extract the uranium from that. Mining operations have a lot of tailings. Uranium rich soils where uranium has been sort of taken out but has been taken out. Dumped on indian reservations.
Move toward indian rights, and had to decide what to clean the tailings up to. It originally appeared as a clearance criterion for clean up of radio active sites. When we clean them we assume linear no-threshold and we can afford to bring them down to 4. we have no idea what 4 leads to. We don’t know if it is a threshold – or anything like that but we can afford to bring a house down to 4. it was a clearance criterion on indian housing. Then a year or 2 later there was a simon watrous incident. Simon watrous worked at a PA nuclear power facility. And every day he would leave the facility and he would leave the facility and he was glowing. On a lark measured on his way in and he was glowing even more. Measured his house at 20,000 PciL. Became a radon mitigator. With that ppl asked if we should coorect all of the houses. Someone said they have a clearance criterion and we’ll bring them down to 4. Bill Rose wrote a paper on where the number came from. Wrote in terms of 100 working levels.
Have to check the relationship between working level and pico curie per liter. But its what was used when it first came out.

19. The Story of Stanley Watrous
The Watrous house tested at 2,700 picocuries per liter,
700x the recommended level.
e discovery in a Center Valley home last fall of the highest radon reading ever in Pennsylvania has its roots in a mystery that started in Berks County almost 30 years ago.
For Brian Redmond, professor of geology and chemistry in Wilkes University's Department of Environmental Engineering and Earth Sciences, the story that brought radon from obscurity to well-known household hazard is one worth recalling.
"Pennsylvania's the reason this all exists," Redmond recently said.
Radon is a colorless, odorless, radioactive gas that occurs naturally through the breakdown of uranium in soil and rocks, entering structures through cracks in the foundation or other openings.
About one in 15 homes in the U.S. has elevated radon levels, and radon is responsible for approximately 21,000 lung cancer deaths a year, according to the federal Environmental Protection Agency.
It was a strange coincidence in a new eastern Pennsylvania nuclear plant 30 years ago that first brought the threat of radon to light.
Redmond was involved in radon research in the 1980s, when awareness of the problem first surfaced.
He said the story started Dec. 14, 1984, at the then new Limerick nuclear power plant in Montgomery County.
One of the employees, Stanley J. Watras, set off the radiation monitoring devices.
"He went in and the thing went crazy," Redmond said.
What was odd was that at the time, there was no radioactive material at the site that could have triggered the detectors.
However, the devices were accurate, Redmond said.
Watras was covered with radioactive material — but it wasn't from the plant.
As it turned out, the Watras family's new house in Colebrookdale Township, Berks County, had massive amounts of radon in it.
News on the discovery broke about a month later and the story quickly spread internationally.
In weeks to follow, the state Department of Environmental Protection — then known as the Department of Environmental Resources — worked to track down the source of the radon.
That's where Redmond came in: "I'm a geology professor, so when all of this hit, they wondered where the radon was coming from," he said.
Redmond, a Detroit native, holds degrees from Michigan State and Rensselaer Polytechnic Institute. In addition to his tenure at Wilkes University, where he has taught in different areas including geology, geography, environmental science and astronomy since 1976, he volunteered for several years with the Peace Corps and also has done research and consulting, including work with radon.
Along with a physics professor, Roger Maxwell, Redmond tried to correlate the high radon levels in Berks County with a physical cause.
As it turned out, the Watras house was on the Reading Prong, a belt of uranium-rich rock stretching from the Reading area to northern New Jersey, passing through the Lehigh Valley.
Although found in trace amounts in rock and soil almost everywhere, the radioactive element is particularly associated with certain kinds of rock, including granite and black shale, Redmond said. The Marcellus Shale, the source of massive amounts of natural gas in Pennsylvania, is also high in uranium, he said.
Uranium decays into radium, which in turn decays into radon, a colorless, odorless chemical element. Radon is a gas, and it decays down fairly quickly, but it remains floating in the air for some time, Redmond said. Radioactive particulates — called "radon daughters" because they continue to decay and emit radiation — will settle on surfaces, as they did throughout the Watras house, he said.
The Watras case made state and federal environmental agencies realize that radon in peoples' houses could be a problem, Redmond said.
Within months, as scarce radon kits became available, the state began to test in the Lehigh Valley, turning up positive results.
Although there are no short-term risks associated with radon, long-term exposure can lead to lung cancer, and it is second only to smoking as the cause of the disease, according to the National Institute of Health.
The discovery of residential radon and its risks made headlines around the world, and spurred U.S. government agencies to take action. The EPA had to come up with an acceptable level for indoor radon, and settled on 4 picocuries per liter. A picocurie is a measurement of radioactivity related to the rate of decay.
The Watras house tested at an astounding 2,700 picocuries per liter — almost 700 times the recommended level.
Today, residential radon testing is "as common as testing for termites," as Redmond put it, but in the 1980s it was a new territory.
Redmond was a certified radon tester and mitigator in those early days, but, he said, "As it became routine, I pretty much backed out of it."
Watras would also get into the field, becoming a certified radon mitigator, per newspaper accounts. Efforts to reach him for this story were unsuccessful.
Redmond thinks the risks of radon are "a little bit inflated." The level of 4 picocuries per liter is based on a yearlong testing of radon in a house under normal conditions, he said. Short-term test results can be 4 to 6 times higher than the results of annual tests, he said.
Nonetheless, Redmond does advocate having homes tested — just in case it turns out there are high levels of radon.
"Until you test, you don't know," he said.
Last fall, the highest radon level ever recorded in Pennsylvania — 3,715 picocuries per liter — was discovered in a house in Upper Saucon Township. Officials said the homeowner decided to do the test.
The detection in the home, and high levels in several others, led the state to issue a call to homeowners in the Center Valley area to have their homes tested.
The high level of radon discovered in Center Valley even took remediation professionals by surprise.
"I was kind of shocked to see radon levels were over 1,000," said Bill Brodhead, whose company, WPB Enterprises, has been installing radon mitigation systems in homes since the 1980s.

20. How to measure radon and variability in results

21. Measurement of Radon Many methods SHORT TERM - 2 – 4 day tests
For example, short term electrets with short term sampler
Sampler
An E-PERM®, also known as an Electret Ion Chamber (EIC), is a passive integrating ionization monitor consisting of a very stable electret mounted inside a small chamber made of electrically conducting plastic. The electret, a charged Teflon® disk, serves as both the source for ion collection and as the integrating ion sensor.  Negative ions produced inside the chamber are collected on the positively charged electret, causing a reduction of its surface charge. The measurement of the depleted charge during the exposure period is a measure of integrated ionization during the measurement period. The electret charge is read before and after the exposure using a specially built non-contact electret voltage reader referred to as the SPER-1 Electret Voltage Reader. Using this data as input to the appropriate formula, one can determine the radon activity present over the duration of the test. 
The basic components of the E-PERM® System consist of the electret reader, chambers, and electrets. There are chambers of different sizes and electrets of different sensitivities to meet a wide range of monitoring situations. Typically, a more sensitive electret, referred to as an ST Electret, is used for short-term measurements, and an LT, or less sensitive electret, is used for longer term measurements. They are known as “true integrators” because they are constantly collecting and “registering” the ions generated by the radon decaying inside the chamber.
Rad Elec Company
Electret

22. Measurement of Radon Charcoal canisters - ~ 2 – 7 days, averaging
Most common type of test kit
This test kit is great for short term testing from 2 days to 7 days. Detectors are analyzed the day they are received at the lab and results are available by phone, fax or that same day!
Each charcoal canister contains activated charcoal. Radon is adsorbed onto the charcoal and then measured at our lab by counting with a sodium iodide detector.

23. Measurement of Radon
LONG TERM - Alpha- Tracks (~91 days or greater, averaging)
LONG TERM ion chambers, more than 3 weeks, any period, averaging
The Alpha Track AT-100 radon monitor is a diffusion-based track detector originally designed in The current improved design filters out dust and radon progeny through a structural filter that is an integral part of the housing, resulting in increased sturdiness. The housing is injection molded from electrically conducting plastic in order to minimize electrical charge effects from the positively charged radon progeny generated inside the detector. The hemispherical base is designed to maximize sensitivity and create a more uniform track distribution for better counting statistics.
The track detector foil inside the housing is from dosimetry-grade CR-39 cast for AccuStar Labs. The sheets of CR-39 are laser cut and engraved with a unique batch number. Each batch is calibrated and receives its own calibration factor. All sheets are also checked for background tracks.
Each detector is given a unique bar coded number and sealed inside an air-tight pouch. The unique Nu-Clear pouch is transparent, which prevents any labeling errors from occurring.
AccuStar Labs remains the only laboratory in the United States to use electrochemical etching to process its alpha track foils which are subsequently counted with computer-aided image analysis equipment. This kind of system was found superior to chemically etched alpha track radon detectors in an article comparing radon detection methods by John Matuszek of the New York State Department of Health (J.M. Matuszek, et al., "Standardization of Radon Measurements", Environmental International, December 1988).
All detector foils are counted using a computer-aided image analysis system. The automated equipment is quite reproducible; rereads of the same group of foils have a mean within 2% of the original mean and coefficient of variation of 5%. Large numbers of tracks can be counted, thus improving range and precision. The detector has an uncertainty of only 12% with a three-month 4 pCi/l exposure. The lower limit of detection is 0.4 pCi/l.
AT-100 Specifications
Rugged structural filter for both indoor and outdoor use
 Twin removable serial labels, human and bar code readable
 Electrochemical etching for better track resolution
 Clear direct read pouch reduces serial errors
 Large foil area counted for better statistics (over 40 square mm)
 Hemispherical housing base for better track distribution
 Electrically conducting housing reduces charge effects and clustering

24. Measurement of Radon ANY DURATION– Continuous Radon Monitors
IS a CRM an ION chamber?
CRM makes counts doesn’t average.
Put in some photos with this of different test methods.
Be more clear.
What an electret is – (out electrets) the y are charged material and when an alpha particle hits the material, it loses some of its charge. Bounce onto it and loses charge.
Radon books?
Browse books from the lung association. CRMs, electrets, alpha track detection, activated charcoal adsorption. Impinges on surface and sticks there.
Most of our work with electrets and CRMS.
10 Days max – Hourly Data
Modified for research - Hourly Data, Unlimited Days

25. Measurement of Radon What EPA says (EPA 1993): Do a short-term test
Radon < 4 pCi/l
4 pCi/l < Radon < 10 pCi/l
Radon > 10 pCi/l
Do a second test
Preferably at least 90 days
Can also do a second short-term
If you think you have to fix it over 4, that’s not what epa says. If you’re under, your done. Between 4 and 10, do 2nd test 90 day or more. Depending on average, you mitigate or not. Epa doesn’t say fix at 4. they say do long term test.
ST: average < 4?
LT: < 4?
ST: average > 4?
LT: > 4?
You are done
Mitigate

26. (or agree on an allowance with the buyers)
Measurement of Radon
What is usually done (esp. for real estate transactions):
Do a short-term test
Radon < 4 pCi/l
4 pCi/l < Radon < 10 pCi/l
Radon > 10 pCi/l
You are done
Mitigate
(or agree on an allowance with the buyers)

27. Measurement of Radon
Remember, action level is intended to be an ANNUAL AVERAGE
Lots of work on variability by Steck et al.
Variability around an annual average for multiple periods
Annual variability (year-to-year)
Get familiar with Steck this weekend!!! He has a table that’s worth showing. Bill can get that for me. He measured the variability. He said that if you have a 4 day test, you have a x% chance of being above or below.

28. Steck et al. variability around annual average (Steck 2005)
Low in winter, high in summer. Consistent with our research. But also inconsistent with general conventions on radon – testing high in the winter.

29. Steck et al. variability around annual average (Steck 2005)
Coefficient of variation. The standard deviation divided by the mean. If we have 2 data sets, annual and sample, 2 data sets for each house. 2 measurements. Can run standard deviation and have the same units. Mean will have the same units. If 1 standard deviation is 76% of mean value then that’s a lot of fluff. 2 days house closed, we’re not really learning anything.
Standard deviation. 2/3 within 76% 1/3 off by more than 76% COV – 1 std. dev. / annual avg.

30. Building America – Site 3 – Living Level
Site 3 living level Even the 2 week average has times than are > 4 and < 4. if trying to make choices for above and below 4 the 2 week avg is not reliable. These tests in context of real estate transactions are “can I get out of paying for a system” test…. Don’t want to do 2 of them. There are reasons four short terms tests, but lets not pretend short term is necessarily accurate representation of a home.

31. Weather Radon higher when temperatures are warmer
Radon Site 1 Living Level
Pay attention to frost lines – trend does not reverse when temperatures are below freezing (or above freezing)
Rain? Not much rain in the sample period to make a difference.
Outdoor Temperature, F

32. Foundation Living Level Site 1 Site 2 Radon Temperature Site 3 Site 4
OPPOSITE OF CONVENTIONAL WISDOM
(From Building America Study Sites 1 – 5)
Foundation top graph
Living Leven is below.
All graphs show lower radon at colder temps. Most clear in foundation.
Site 2 is weird. He never opened his windows in his house. There was good mixing between crawl space and the house.
Site 3
Site 4
Site 5

33. Colder temperatures – what is going on?
Don’t know for sure
Hypotheses:
Yes, there is greater stack effect pulling on the ground, but there is also greater dilution and more of that comes from outside than the ground
HVAC operation – may (1) mix and get radon upstairs; and (2) increase air exchange rate (i.e., get it up and out)
Bill Rose – lower soil temps = higher soil moisture content and radon is soluble in water? (Untested)
Colder temperatures, radon goes down. Why is that? We don’t’ know for sure. Yes there’s a greater stack effect, buoyant stack affect in the house. Will make lowest level more negative which in theory should pull more out. But there’s also greater dilution and more comes fro m oustside. Net effect/ greater contribution / greater dilution thanks to stack comes from outside the ground. And with HVAC operation and get radon more quickly upstairs and once upstairs it gets out.
3rd hypothesis – soil in winter is wetter in winter than in the summer. Radium in soil decays, creates radon atom that goes into soil gas. If you have coat soil particle with water, or ice, the radium will still decay to become radon – soluble in water. Soil water might become richer and soil gas might become weaker. Winter time soils tend to be wet and soil wetness impacts ability of soil to produce and project radon.
No one associated with skin cancer or stomach cancer.

34. How good are various test methods?
Probably all pretty good at measuring what happened when they were there.
Instrumentation itself is not problematic.
The problem is that radon is so variable – levels you see this 2 or 4 days may not be the levels you will see 2 or 4 weeks from now.

35. Our Research Studies

36. HEALTH-V Study
The HEALTH-V study evaluated health and environmental outcomes associated with two ventilation approaches taken in existing homes. The number of homes studied was 52 in the Chicago area and 35 in Indiana. The control homes were weatherized based on ASHRAE and the treatment homes were ventilated to ASHRAE , both in the course of weatherization (wx) energy retrofit.
Ventilation for each house was randomly selected to comply with either ASHRAE or ASHRAE Under ASHRAE , a lower limit of airtightness is established and the air-tightening is conducted down to the tightness limit, but no further. As a result, the homes complying with ASHRAE did not, in actuality, receive whole-building ventilation, but relied on passive infiltration. Under ASHRAE , the air tightening is conducted to achieve the maximum airtightness achievable, and mechanical ventilation is introduced to meet ventilation requirements, relying on active infiltration.

37. Goals and Methods Compare benefits of differing ventilation standards
ASHRAE vs. ASHRAE 62.2
Observe changes in IAQ from energy retrofits
Formaldehyde, Total VOCs, Radon, CO2, CO, Humidity
Conduct preliminary and final health surveys

38. Sites Tested Tested 52 homes Chicago area, 35 homes in Indiana
Randomly selected
Control homes weatherized to ASHRAE (passive infiltration)
Treatment homes weatherized to ASHRAE (mechanical ventilation)

39. Exhaust ventilation Radon, basement Radon Number (n) Mean (pCi/l)
Geo-mean (pCi/l)
T-test p-value
Pre-Wx all 51
5.1
2.6
0.330
Post-Wx all
6.0
3.0
Pre-Wx 23
6.3
0.888
Post-Wx
6.7
2.9
Pre-Wx 28
4.2
2.4
0.073
Post-Wx
5.4
3.1
– not statistically significant. Basement radon increased with Average went up from 4.2 – 5.4.
Green indicates statistical significance at p < 0.10

40. Exhaust ventilation Radon, 1st floor Radon Number (n) Mean (pCi/l)
Geo-mean (pCi/l)
T-test p-value
Pre-Wx all 46
2.7
1.8
0.143
Post-Wx all
2.6
1.4
Pre-Wx 21
2.4
1.7
0.824
Post-Wx
2.8
1.6
Pre-Wx 25
3.0
1.9
0.067
Post-Wx
1.3
Statistical significant at 90%
Green indicates statistical significance at p < 0.10

41. Building America Study
Conducted by researchers at ICRT, homes in Champaign, IL
Intended to evaluate potential for air sealing between foundation and first floor to reduce radon migration
Principle of “do no harm” as opposed to solving high radon problems
Isolate foundation from the living space.

42. Objectives
Investigate effectiveness of targeted floor air sealing at isolating the living space from the foundation space
Monitor effect of air-sealing on radon levels in foundation and living spaces
If specific air-sealing targets can be prescribed to address radon levels
Discover the role that ductwork plays in the transport of radon to the living space

43. Sample House Characteristics
3 Groups: Fall 2013, Spring 2014, Summer 2014
11 Crawlspace, 4 Basement + Crawlspace(s)
Average home age: 1966; Newest: 2005; Oldest: 1890
Average CFM50: 3239: Tightest: 1542; Leakiest: 5896

44. Study Design
15 homes monitored in 3 groups of five monitored for ~90 days
Monitor for a month
Retrofit 2-3 of them, monitor for a month
Retrofit the others, monitor for a month
Monitoring was continuous in living level, crawlspaces and basements
For each set, we had 3 months.
Divided 5 houses into 2 clusters.
For two houses, did treatment at beginning. Could say we had controls. Pre-treatment, post treatment, and those with no treatment as control. Then use the first 2 as control. No treatment to compare to pre and post that received treatement. Giving treatment to everybody and having the opportunity for controls. IN the end we just threw out the controls, they didn’t work. Purpose of control is to correct for outdoor conditions. When we did r squared comparison, they didn’t agree. They had nothing in common.

45. Retrofit Measures Applying mastic and foil tape to duct work
Expanding urethane foam at penetrations beneath the floor
Repairing or replacing degraded missing duct work

46. Wide open ducts in crawl space
BEFORE
AFTER

47. Windows Open / Closed

48. Basements and First Floors track each other?
Site 5
Site 3
r2 =
r2 =
Radon levels in basement do not explain living level that well.
Greatest agreement
Worst agreement

49. 𝟔 𝟏𝟓 Reduced; 𝟐 𝟏𝟓 Even; 𝟕 𝟏𝟓 Increased
Results
Treatment lead to measureable change in zone pressure measurements with greater isolation of foundation and living space.
Improved isolation did not lead to statistically significant change in living level average radon
No changes could be conclusively attributed to the treatments.
𝟔 𝟏𝟓 Reduced; 𝟐 𝟏𝟓 Even; 𝟕 𝟏𝟓 Increased

50. Case Studies
Air handler fan ran continuously – living level and crawl radon were within 10%
Very large return duct leaks – after sealing radon noticeably dropped

51. National Weatherization Evaluation
Report released 2015
Weatherization and Indoor Air Quality: Measured Impacts in Single-Family Homes Under the Weatherization Assistance Program
Scott Pigg, Energy Center of Wisconsin
Dan Cautley, Energy Center of Wisconsin
Paul Francisco, University of Illinois
Beth Hawkins, Oak Ridge National Laboratory
Terry Brennan, Camroden Associates

52. Sites Tested 514 single-family homes 35 states
88 weatherization agencies participated
2010/2011 heating season
Over sampled in high – radon areas
Tested radon using activated charcoal canisters
7 day test before and after Wx

53. Key Take Aways
Average single-family home had heating-season indoor radon levels of 1.9 ± 0.1 pCi/L
Tighter homes tend to have higher radon levels
Data suggest Wx results in small, statistically significant increase in radon levels.
Average increase of 0.4 ± 0.2 pCi/L
Most states Wx programs used ASHRAE (Building Tightness Limit)
Study technicians deployed 7-day, activated-charcoal canisters to measure radon levels in foundation spaces and first-floor living spaces before and after weatherization. These tests were made during the heating season under closed-home conditions. These short-term tests are thus not reflective of expected annual average radon levels in weatherization homes. Key findings for radon follow:  The study data indicate that the average single-family home in the program has a heating-season indoor radon level of 1.9 ± 0.1 pCi/L.  Pre-weatherization radon levels are correlated with pre-weatherization air tightness: tighter homes tend to have higher radon levels.  The study confirms that elevated radon is relatively rare in mobile homes and in site-built homes in counties identified by EPA as having low radon potential.  The data from the study suggest that weatherization results in a small, statistically significant (in absolute terms) increase in indoor radon levels. Nationally, the study data suggest an average increase of 0.4 ±0.2 pCi/L.  The impact of weatherization on radon appears to be generally proportional to pre-weatherization levels: homes with low pre-existing radon levels – which constitute the majority of program homes – experience only a slight increase in radon levels on average, while homes with pre-existing elevated radon experience a larger average increase following weatherization. On average, the radon impact is thus largest among site-built homes in EPA high-radon-potential counties, and lowest among mobile homes and homes in low-radon potential counties.  Changes in measured air-leakage rates due to air-sealing efforts —which are intended to reduce air infiltration and yield energy savings were found to be statistically correlated with changes in radon levels in study homes.  The study provides some evidence that the installation of continuous mechanical ventilation reduces radon levels in homes.

54. Researcher Scott Pigg, Energy Center of Wisconsin
National Weatherization Assistance Program Impact Evaluation: Impact of Exhaust-Only Ventilation on Radon and Indoor Humidity – A Field Investigation
Researcher Scott Pigg, Energy Center of Wisconsin
Evaluated 62.2 compliant exhaust ventilation
18 homes in Colorado, Iowa, Minnesota and Ohio
Toggled on/off ventilation and results suggest that compliant exhaust ventilation can reduce radon levels.
The study involved 18 homes in Colorado, Iowa, Minnesota and Ohio

55. Paul Graphics

56. results bit.ly/ORNLWxEval
Radon levels declined or remained about the same for all homes in the study when the ventilation was operated.
On average, the installed ventilation reduced radon levels by 12 ±7 percent.
This suggests that in most cases, the dilution effect of exhaust-only ventilation outweighs any tendency to increase the radon entry rate by depressurizing foundation spaces.
FIND THE REPORTS AT
bit.ly/ORNLWxEval

57. Building Assessment of Radon/Moisture Reduction w/ Energy Retrofits (The BARRIER Study)
University of Illinois at Urbana-Champaign
National Center for Healthy Housing
Tohn Environmental Strategies
11/10/2018

58. Need for the Study Questions:
Can low-cost, passive measures that are aligned with normal weatherization measures keep radon levels from increasing as a result of WAP activities?
Are there also moisture benefits?
11/10/2018

59. Enhanced Measures
Crawl spaces
Plastic groundcovers carefully installed such that all seams are sealed and the plastic is sealed to the perimeter walls and any foundation supports
Air sealing of ducts located in the crawl space
Air sealing of the floor between the living space and the crawl space
Air sealing around any interior crawl space accesses

60. Enhanced Measures Basements
Plastic groundcovers over any exposed earth, carefully installed such that seams are the plastic is sealed to concrete
Installation of sealed sump pump covers
Caulking of cracks in below grade concrete
Air sealing of the floor between the basement and first floor, if the basement is not the lowest living level
Air sealing of return ducts located in the basement
So far results are not inconsistent with other studies but the sample size is small.

61. Conclusions What we’re still learning Impact of retrofits
Impact of ventilation, esp. exhaust
How weather impacts radon
Results suggest opposite trend from “known” trend
Variability between houses from same weather exposure
Variability from basements to first floors within homes
(We are currently working on these issues)

62. Questions?
For more information contact

63. Radon vs. stack effect/air sealing
Where do we air seal?
Most is at ceiling, some also at floor

64. Radon vs. stack effect/air sealing
What happens when we air seal at the floor?
Reduces radon entry potential by reducing pathways

65. Radon vs. stack effect/air sealing
What happens when we air seal at the ceiling?
Neutral level goes lower
Reduces negative pressure on the ground

66. Radon vs. air sealing
So, when we air seal at the ceiling, we do indeed make it harder for radon to get out, but we also make it harder for radon to get in
When we air seal at the floor we also make it harder for radon to get in
On balance? Difficult to say, but at the very least it is clear that the assumption that radon entry is unchanged is an assumption that should be rejected